The Assessor Mag Autumn 2024 Web - Flipbook - Page 32
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see the allowable repair process from
the vehicle manufacturer, and develop
the repair plan. We know the effect
on other systems such as SRS or
seat belts, the difference between a
structural element and a non-structural
element. That knowledge was
developed over decades of hard-won
testing by manufacturers, and equally
hard-won knowledge assimilation by
IAEA members.
For traction batteries, this knowledge is
still in development.
Until recently most manufacturers
provided comprehensive information
about high-voltage precautions, the
type of necessary training, the type
of equipment to use as well as how
to safely remove / install assemblies.
Soon, full strip and re-build of traction
batteries was added to vehicle
manufacturer information.
engine drive and MHEV. Latest
applications also include PHEV. These
platforms have evolved as a lower cost
mass market solutions – the ‘kit’.
Stellantis publish all the usual and very
important information, and of course,
anyone attempting any repair on a
high voltage vehicle should be suitably
quali昀椀ed as well as equipped. The
process begins by powering down the
vehicle, taking note that our biggest
hidden assets are the electric coolant
pumps to manage traction battery
heat (assuming enough of the electric
system functions) and the battery
control module which activates the
pumps.
Next step is to assess the underside,
using the Stellantis guide. This is from
Peugeot e-208:
Next step is to check the distance
between all the mounting points, as
con昀椀rmation that the battery case is
damaged:
The problem is how to assess the
internal cell level damage caused by
bending the case as it passes over
debris in an accident. The lower case
could make contact because a wheel
has been ripped off, the secondary
impact was with the road-side or fences
or parts of other vehicles.
We do know this matters.
In time, newer battery technology will
get around the internal shorting issues
that could occur in most Li-Ion packs,
but until that happens, we are left with
an ever-growing 昀氀eet of cars, LCVs,
HGVs and PSVs equipped with this
technology. Should an internal short
occur, depending on how much energy
is stored at the time, will affect how big
the disaster will be.
However, many vehicles do get
underside scars and don’t go up in
smoke.
Vehicle manufacturers are starting
to address this knowledge gap, and
Stellantis is one for the 昀椀rst to do so
– a process to scope allowable case
deformation.
First steps
The widely used Stellantis CMP and
EMP2 platforms are available with pure
electric drive, pure internal combustion
32
The blue areas marked are reference
faces. Using a straight bar ‘m’, resting
against those reference faces, it is
possible to measure the distance to
the rest of the case. The document
gives detailed view of each zone, and
measurements.
For example, in the front section
we can see the dimension ‘L’ is in a
red zone. So, is the measurement
exceeds 6.2mm, the battery should be
replaced.
The missing information
Few know how to assess traction
battery lower case damage. Imagine
that early mobile phone battery, which
could have been thin enough to bend
(not advisable). Now apply that to a
vehicle traction battery – even less
advisable.
Any deformation in the ‘red’ zones
requires replacement of the traction
battery. So, we can assess the
condition of the battery from the
underside without having to remove it
昀椀rst…
In this application the battery modules,
and so the battery cells they contain
are distributed across several zones,
unlike the BMW i4 G26. Stellantis have
worked through the distance between
the lower case and the modules right
across the entire assembly.
The measurement ‘M’ refers to a yellow
zone, so if that exceeds 9mm, but is
less than 13mm then Stellantis are
happy to consider the traction battery
could be used – subject to further
diagnostics-based checks.
Similarly, if any of the coolant couplings
to the traction battery are damaged,
the traction battery must be replaced:
The colour codes:
• Green – permanent deformation
is allowed between 4mm and
10mm
• Yellow - permanent deformation
is allowed, less than 4mm
• Red – no permanent
deformation is allowed (0 mm)
While any Li-Ion battery has ‘no moving
parts’ as such, it is made from many
parts – all of which have to be in near
perfect condition for the assembly to
work. The biggest key for assessment
is to see that the case does not have
signi昀椀cant underside scars, the cooling
/ heating system remains functional
and the body has protected the rest of
the battery assembly.
These are important but early steps.
It shows us immediately how dif昀椀cult
traction battery condition assessment
can be, and how some manufacturers
are trying to assist.
JOURNAL
THE ASSESSORS JOURNAL | AUTUMN 2024 | www.iaea-online.org/news/the-assessor
